An end effector is a tool on the action arm of a robot used to handle materials, perform procedures, or control activities. End effectors have sensors that give them information and communicate to the robot controller that items are in place, missing, or available; that procedures have been completed or a fault or collision occurred. In the following references, which are incorporated herein for all purposes, layer picking end effectors are described and have been in use for many years.
U.S. Pat. No. 3,387,718, titled “Pallet Loading and Unloading Apparatus,” to Roth et al., relates to an apparatus for loading and unloading pallets that support multiple layers or tiers of articles, such as packages, boxes, cases for beverages, and other articles to be handled in rigid or semi-rigid containers of wood, paperboard or fiber materials. Conveyor means bring or take away articles from the apparatus. When the conveyor means brings articles to the apparatus, the articles are formed into layers having a desired pattern. After the layers are formed the layers are moved onto a belt. When the conveyor means takes articles away the entire layer is moved off the belt and dispersed by the conveyor means. As part of the apparatus, members seal off the periphery of the layer, and concurrently, push the articles into a compact arrangement to substantially reduce air flow past the article.
U.S. Pat. No. 3,404,787, titled “Suction Lift for Article Distribution and Storage System,” to Hayford, et al. is directed to a suction lift for article distribution. The suction lift includes a hollow, moveable head; an open grate movable vertically with respect to the hollow, moveable head; and a flexible curtain depending from the rigid top of the hollow. The open grate is pervious to the movement of air so that suction is readily applied through the grate. The grate is moved vertically downward from the rigid top of the head when a single tier of units is to be lifted and is moved upward toward the rigid top of the head when more than one tier of units is to be lifted. Lifting of a plurality of tiers is improved if the depending curtain is held away from all but the lowermost of the tiers when suction is applied. The Hayford apparatus utilizes a vacuum to lift tiers of units.
U.S. Pat. No. 3,556,579, titled “Suction Pads,” to Seymour-Walker et al., describes a suction pad having side portions depending downwardly from a top portion and adapted to be brought into a gripping relationship with the side faces of an article to be lifted by the pad. In one embodiment, the pad presents a lifting surface to the top surface of the article. The Seymour-Walker apparatus utilizes suction with a suction pad to lift an article.
U.S. Pat. No. 4,850,627, titled “Packaging Handling Method and Apparatus,” to Franklin, addresses the transfer of a collation of flexible packages from a first location to a second location by employing a loading head. The loading head includes an enclosure having an opening and a permeable barrier extending across the opening. The opening and the collation of flexible packages are brought together at the first location. Suction is applied to the enclosure drawing air into the enclosure through the permeable barrier. Packages are drawn against the barrier by the air drawn through the permeable barrier and thus upper regions of the packages are expanded towards one another by sub-atmospheric air pressure created by the suction. The packages tend to seal against one another and to prevent flow of air through the collation, so that the collation is held by suction against the barrier. The enclosure is transferred to the second location and the suction is removed to release the collation from the enclosure. Apparatus for carrying out this process incorporates a motor-driven radial flow fan without an external shroud mounted on the enclosure to generate the suction. The Franklin apparatus utilizes a vacuum to lift a tray.
U.S. Pat. No. 5,088,878, titled “Apparatus for the Lifting of Tray Packs,” to Focke et al., discusses that the lifting and transportation of sensitive articles incapable of bearing a mechanical load, without manual involvement, presents special difficulties in packaging technology. This applies, above all, to tray packs in which articles are arranged standing on a bottom part of small height, without any additional anchoring. For grasping and lifting articles of this type, the Focke reference describes a raisable and lowerable suction box which, with suitable dimensions, is placed over the article in a manner of a bell. By the generation of a vacuum within the suction box, the article (for example, tray pack) is held carefully and can be lifted by means of the suction box. Side walls of the suction box are arranged pivotably, to make it easier to place the suction box onto the article.
Although the above-mentioned devices are useful in their own right, an improved handling of articles is attainable with the present invention. The inventors have invented a hood style end effector which has four sides that are made of a material with limited flexibility, e.g., sheet metal, and can close around the bottom of a layer of cases, conform to whatever rectangular size the specific layer is, and have special corner members that provide air leakage control. Additionally, the present invention can detect the occurrence of slip sheets, and the dropping of lifted product.